Chapter 1 part 1: Length and Time

                                            General Physics

•  1.1: Length and time.
  
  For the beginning of your IGCSE Physics course you will need to be familiar with the idea of measurement.

We can measure distance in the SI base unit Meters (M) and time in the SI base unit Seconds (S)
You will need to know some rules about measurement. We can measure using two kinds of apparatus
Digital and Analogue 


A digital display shows one value at a time , while an analogue display , such as in a car speedometer, shows a range of values


For very small increments of time in the case of fast moving objects, we can take an average over many experiments.
E.G. If a pendulum swings quickly from side to side , in order to find the time for one oscillation. you will time how long it takes for 10 swings, and divide that number by 10
To measure time we can use a clock or stopwatch.To measure distance we can use meter rules or tape measures for lengths, and use micrometer screw gauges and vernier calipers for thicknesses

Q&A:

Q:How to measure the length of a string without a ruler ?
A:First, we can wrap the string around a cylinder as many times as possible for the full length of the string. for example , if the string goes 3 times around the cylinder , and the cylinder has a diameter of 3 cm , then the string is 9 cm long.